1. Field of the Disclosure
The disclosure relates to an optical fiber and an optical transmission system.
2. Description of the Related Art
With the recent dramatic increase in the Internet traffic, it is expected that transmission capacity will be insufficient in the future in optical transmission systems if only a fundamental mode of optical fibers are used in signal transmission as conventionally done. Spatial multiplexing techniques using multi-core optical fibers and mode multiplexing techniques using multi-mode optical fibers are regarded as promising methods for solving the insufficiency in the transmission capacity.
A method of widening a wavelength bandwidth of signal light is also effective for increasing the transmission capacity. For example, K. Ieda et al disclose in “Visible to Infrared WDM transmission over PCF”, ECOC2006-Tu3.3.4 (2006), ultra-wide bandwidth transmission experiments over a range of a visible light bandwidth to a communication wavelength bandwidth using a holey fiber of 1.0 km in length.
The holey fiber (HF) is an optical fiber that achieves optical transmission by regularly arranging holes in a cladding to reduce an average refractive index of the cladding and using the principle of total reflection. K. Imamura, K. Mukasa, Y. Miura, and T. Yagi disclose in “Multi-core holey fibers for the long-distance (>100 km) ultra large capacity transmission,” OFC2009, No. OtuC3 (2009), a multi-core holey fiber including a plurality of core portions.
As described above, an optical fiber and an optical transmission system that have a larger transmission capacity are required to handle the increasing demand for transmission capacity.
Accordingly, there is a need to provide an optical fiber and an optical transmission system that have a large transmission capacity.